In-situ collagen injection in postamputation symptomatic neuroma: A case report

Rationale: Postamputation pain remains a significant clinical challenge, affecting a substantial proportion of individuals with limb loss. Among its etiologies, symptomatic neuromas-resulting from aberrant peripheral nerve regeneration-are a common source of residual limb pain. These lesions often lead to severe discomfort and a considerable decline in the quality of life. Although surgical treatments are available, they are often invasive and carry a risk of complications, especially in elderly or frail patients. Nonsurgical interventions, such as steroid injections, provide temporary relief but lack long-term efficacy. Patient concerns: This case study investigates the use of in situ collagen injections as a novel treatment for symptomatic neuroma in an 87-year-old patient with a longstanding transfemoral amputation. The patient had experienced similar symptoms multiple times before, marked by exacerbation and partial remission periods. However, these symptoms have become more intense and disabling over the past 3 months. Diagnoses: A thorough neurological evaluation revealed no overt motor or sensory deficits aside from pain, hypersensitivity, and tenderness above a soft tissue mass on the posteromedial side of the transfemoral stump. Elicitation of Tinel's sign reproduced both phantom and residual limb pain. A diagnosis of symptomatic postamputation neuroma was established based on clinical criteria and further corroborated by ultrasound imaging, which allowed direct visualization of the neuroma. Interventions: The therapeutic protocol involved 2 ultrasound-guided perineuromal injections of a porcine-derived collagen medical device, administered 3 days apart. Pain intensity and sonographic characteristics of the neuroma were assessed over a 12-week follow-up period. Outcomes: Results indicated a significant reduction in pain 1 week after the second injection, with improvements lasting up to 4 weeks. Functional outcomes, including prosthetic tolerance, also showed improvement. However, the treatment's effect diminished by the 12-week follow-up. Lessons: This case highlights the potential utility of in situ collagen injections as a safe, minimally invasive therapeutic option for symptomatic neuromas. Although the observed analgesic and functional benefits warrant further investigation, collagen injections could offer a new therapeutic approach for managing neuroma pain and serve as a promising alternative to more invasive interventions, especially in the elderly and multimorbid patients.